Oil is the principal form of energy in the world. Its origin is popularly attributed to decayed organic matter formed in the Carboniferous period. In the Applicant's opinion it more probably resulted from hydrogen gas emanating from the earth's core reacting during its ascent to surface with carbon in marine limestone. Oil is mainly employed for locomotion, (automobiles, ships, aircraft,) heating, lubrication and manufacture of organic based materials. Its principal source is as natural pools chiefly in Saudi Arabia, Iran, Iraq, Nigeria, Algeria, beneath portions of the North Sea and the Gulf of Mexico and to a lesser extent in many other localities from which it is recovered by pumping. Oil also occurs in secondary deposits as heavy oil either mixed with sand (e.g. Alberta Canada, Venezuela, Trinidad and USA) or contained in carbonate rock (e.g. Canada), or sandstone (e.g. USA) or is wide-spread internationally in shales (e.g. USA).
Heavy oil has a specific gravity rating according to American Petroleum Industry (API) designation, from 0° to about 25°. It is comparatively more difficult and therefore expensive to recover heavy oil for industrial use from secondary deposits rather than from ones that can be pumped. Moreover with one notable exception, secondary deposits are not very large. The exception is the Athabaska oil deposits in the provinces of Alberta and Saskatchewan in Canada.
The Athabaska oil deposits consist of a number of oil sands deposits plus one in carbonate rocks. The main deposit, the Athabaska (after which the deposits are named), has three smaller satellites, the Peace River, Cold Lake and Lloydminster along with lesser such deposits. They form a north westerly belt across the north-central portion of Alberta extending from about 100 kms (62 miles) north of the town of Fort McMurray southward to within 75 km (47 miles) north of the city of Edmonton. The Athabaska deposit is the largest member being up to 250 km wide by 450 km long (155 miles by 280 miles). The three other principal members are about 20% of its size and the remaining members much smaller.
There are also vast amounts of heavy oil (about 26% of the amount estimated in the oil sands reserves) in carbonate rocks beneath the Alberta oil sands. These latter deposits have about 7%-40% porosity and 100 to 10,000 mDarcies (mD) permeability. These oil sands and carbonate rock deposits together are estimated to contain 2.15×1011 m3 of bitumen roughly equal to 1.51×1011 m3 of oil. This amount is equivalent to about one trillion (1×1012) US barrels (USb) of oil which is the estimate for the Saudi oil field. The Athabaska and Saudi deposits represent the two largest individual accumulations of oil in the world.
The Athabaska oil sands deposits consist of a mixture of about 1% to 15% averaging 8% bitumen (congealed oil) plus minor fine clay and water in high porosity (28%-32%) quartz arenites varying to arkosic sands of Cretaceous age. Their permeability is about 35 Darcys (D). They form flat lying sheet-like zones up to about 20 m (66 ft) thick across the deposits. The zones vary in vertical depths below surface of up to about 400 m (1,300 ft) depending on the overlying overburden thickness and are flanked above and below by sandstone-shales and limestone beds respectively. The overburden consists of muskeg, sand, gravel and clay (largely unsuitable for farming).
Bitumen is a tar like substance comprising various types of petroleum products ranging from asphaltenes to light petroleum with approximate parameters and composition, according to the API, of specific gravity=8°-14°, C=83.2%, H=10.4%, O=0.94%, N=0.36% and S=4.8%. Currently it is initially recovered from the host deposit and then either sold as is or up-graded by distillation plus reduction of S and N and addition of H to become more valuable types of petroleum products. Raw bitumen is worth about 75% of the quoted price of Saudi oil. Accordingly it is initially upgraded into two fractions: one containing about 30% of the bitumen with the heavier hydrocarbons including asphaltenes and the remainder being lighter hydrocarbons similar to Saudi crude. The fractions are refined to more valuable products.
Oil recovery from the bitumen in oil sands deposits presently entails two sequential steps that can be performed in two alternative ways:    1. The upper portion of the oil sands deposit with bitumen is recovered by open-pit mining (OPM) to a depth of about 40 m (130 ft) below surface which is the economic depth of the method. The oil sands are hauled to a concentrator and treated with hot water and caustic soda to release the bitumen which is removed by flotation. The associated sand, water and clay plus un-extracted bitumen (i.e. tailings) are discharged into a tailings pond. The objective is to perform water separation by allowing the heavy minerals (i.e. sand, clay etc.) in the mixture to settle, and the bitumen to float. This process can require many years for the separation to be achieved in the ponds.    2. Bitumen deeper than the economic reach of OPM is usually recovered by steam-assisted gravity drainage (SAGD) or an alternative steam-based technique. It entails the installation into the deposit of two sets of parallel horizontal perforated pipes, one set above the other. The pipes in each set are about 5 m (16 ft) apart. The upper set is fed with steam to heat the surrounding sands and melt the bitumen causing it to flow into the lower pipes from which it is pumped to surface.
These oil mining methods are capital intensive, and invite an environmental nightmare. In fact they have been publicly described as ‘the most destructive ever designed’.
The enormous loss of water due to tailings discharge and as steam for SAGD is forecast together with expected climatic change to deplete the Athabaska River (the main source of water for the system).
Combustion of oil sands products (or natural gas) to generate steam for SAGD creates massive amounts of CO2 greenhouse gas.
OPM removes as much waste volume as it does oil sands, and with tailing pond excavation, it is scarring the landscape beyond recognition.
Only about 43% of the Alberta oil sands plus underlying carbonate rock oil deposits are considered to be economically recoverable by existing technology.
The overall oil recovered from these hosts by current technology is estimated to be 50% of that in the deposit (i.e. about 40% by SAGD and 80% by OPM).
The foregoing issues, especially the Athabaska River depletion, are prompting public outcry about the sustainability of the Athabaska oil sands development. There are rising public demands to terminate oil recovery until this question is answered acceptably. Since commencement of mining in the 1960's the total petroleum output to date from the Athabaska deposits is about 0.3% of their estimated original amount of one trillion barrels of oil. Present mining rates vary from about 1,000 b/day to about 350,000 b of oil/day by 14 companies. All but three of these companies mine oil at much less than 100,000 b/day.
The combined oil mining operations in Alberta currently cover about 10% of the total area of the oil deposits. The balance is untouched mainly due to the huge mining costs involved. A mining system requires about $2 billion/100,000 b/d of oil output. None of the oil contained in the carbonate rocks is being recovered because suitable technology does not yet exist. A nuclear reactor has been proposed to generate electricity to heat the oil to cause it to flow for extraction, however the cost to build this is unlikely to be economical.
Heavy oil also exists in shale deposits with kerogen, an organic material including bitumen and other organic constituents with the formula C215H330O12N5S. Shale oil deposits contain about 3%-5% kerogen plus about 4%-20% oil. They are mined on a limited scale in the Baltic region mainly as heating fuel and to some extent as a source of oil that is recovered by leaching the crushed shale to extract the oil from the kerogen. The largest reported deposit is in Colorado, USA, and is estimated to contain 800×109 barrels of oil. The total amount of heavy oil in the world including that in the foregoing Athabaska and US deposits plus that in such deposits in Venezuela, Trinidad, Indonesia, Oman and elsewhere is estimated to be 6×1012 barrels. The parameters, recovery methods and results for the additional deposits are essentially as described for the Athabaska deposits and the environmental impact from their mining is equally serious. Accordingly all of the said heavy oil deposits are regarded as propitious targets for the present invention.
Various processes for recovering oil from oil sands and the like by solvent extraction and in situ pooling and leaching have been studied especially in the years from about 1970 to 1985. Hot water, steam and petroleum-based solvents and diluents have been tried without real success. To Applicant's knowledge no significant commercial operation of this type has existed: it is understood that high solvent losses, low overall recoveries and other operating problems as well as competitive pressures, have kept such operations from being cost effective. Typical references include: U.S. Pat. Nos. 3,858,654; 3,881,550; 3,929,193; 4,474,238; 4,510,997 and GB Patent No. 2,136,034.
Kenchington et al. in “Energy Sources”, Vol. 5, No. 4, 1981, pp. 317-338 summarizes cost parameters for solvent extraction of mined oil sands using petroleum cuts or blends of C6-C9 aliphatics and aromatics. Brief mention is made on p. 318 of in situ processes for oil sands too deep to mine in which a steam or flame front is generated to drive distilled and cracked product to a recovery well. No direct ISL technique is mentioned.
As used herein, the “oil” in oil sands and other host materials is intended to comprise various petroleum oils particularly heavy oil, bitumen or kerogen and asphaltenes. Normally these recovered oils are subject to various fractionations and hydrocracking to derive desired products.